When will we have flying cars? Maybe sooner than you think.

Two weeks ago I would have said flying cars were still firmly in the realm of techno-utopian fantasy, as they have been for decades. Now I’m not quite so sure.

In the coming few years nearly 20 small airborne vehicles are supposedly hitting the market (see table below). Some are drone-like, with anywhere from four to 18 rotors keeping them aloft. Most are fixed-wing craft with propellers that point upwards for vertical takeoff and landing (VTOL), and tilt forward for flight.

Some are also more realistic than others. While both Airbus and Boeing have projects under way, a raft of smaller companies are pushing aggressive time lines as well. Germany’s Volocopter plans to starttrials this year of a flying taxi in Singapore. Uber has claimed it will start test runsnext year for a service between Frisco, Texas, and the Dallas–Fort Worth airport,and that it plans to start commercial flights in 2023; it has five flying-car makers as partners.

But will they ever be safe, let alone affordable for anyone who isn’t mega-rich? At the World Economic Forum in Davos last month, I moderated a panel of experts who made a persuasive case that they could be—though, to be fair, most of the speakers had an interest in doing so.

The panelists were Dirk Carsten Hoke, CEO of Airbus; Ross Perot Jr., a Texas real estate mogul who is helping Uber start up the flying taxi service in Dallas; Liu Fang, director-general of the International Civil Aviation Organization; and Ion Yadigaroglu, a managing partner at Capricorn Investments , which has a stake in Joby Aviation. The panel was under the Chatham House rule, which means I can’t report specific statements, but this was the gist.

Why are so many flying cars launching in the next few years?

Lighter composite materials, better communications and guidance systems, and software that could enable the vehicles to fly themselves (probably essential if there’ll be a lot of them in the air) have all played a part. Above all, battery technology is on the verge of making electrically powered flight feasible. We’re still some way from the energy density needed for flights of any length, but short hops aren’t completely out of the question.

But wait—are these literally flying cars?

Not really. A few, like the Aeromobil and the Terrafugia Transition, are cars you could drive on the highway, but most are more like personal flying vehicles .

So, um, helicopters?

Nope. Most have wings that generate lift, like ordinary planes. A few have multiple rotors, like drones. Either way they are, theoretically at least, safer than choppers (see below).

When can I buy a flying car?

Sorry, you probably won’t be able to. At least for now, you’d need to be a certified pilot (or employ one) to fly it, and besides, where would you park it? They’ll mostly be owned by firms such as ride-sharing companies and run on fixed routes.

Will flying cars be autonomous?

Ultimately, they probably will be; human pilots are expensive and might not be reliably safe in a really crowded sky. Autonomous flying is an easier technical problem than autonomous driving: obstacles in the sky are few and can be detected with simple radar, whereas a self-driving car needs multiple sensors and heavily trained algorithms to recognize people, other vehicles, traffic signals, lanes, and so on. An automated air traffic management system in constant communication with every flying car could route them to prevent collisions, with human operators on the ground ready to take over by remote control in an emergency. Still, existing laws and public fears mean there’ll probably have to be pilots at least for a while, even if only as a backup to an autonomous system.

Where will flying cars fly?

Places where demand is high and road traffic is bad—within large cities or from city centers to airports. Rural or intercity travel probably won’t make economic sense.

Where will you catch one?

At “vertistops” and larger “vertiports” on the tops of buildings, which will bring the building owners some extra revenue. (There’d also be chargers or battery-swapping stations there.) That’s how we’ll deal with the problem of finding space in crowded cities .

Won’t rides be insanely expensive?

Again, most of these aren’t helicopters but winged aircraft, so all the propellers’ energy goes into pushing them forward after takeoff, not keeping them aloft. An electric VTOL vehicle’s energy use per mileis theoretically comparable to that of an electric car. Mass production should eventually bring down the prices of the vehicles themselves. The real cost problem might be the pilots (while we still have them, at least).

Still, our panel speculated that a trip of a few miles might cost passengers as little as $40 or $50—a bit more than a ground taxi, but in a congested city you’d get to your destination much more quickly. In a 2016 white paper,Uber had some sunny projections (pdf, p. 1 and p. 95) showing that for certain routes at least, it will actually be much cheaper, as well as several times faster, to take a flying car than a wheeled one.

Is it safe to have hundreds of flying cars buzzing above packed urban centers?

To make vertical takeoff possible, these vehicles need multiple engines that can produce far more power that what’s required for steady flight. That means that if one or two of them fail, the vehicle can still fly or glide to safety. New air traffic management systems will probably rely more on algorithms than humans to manage the routing—another reason why it’s better if the aircraft flyautonomously .

Okay, but what about a terrorist taking over a flying taxi and crashing it into a building?

As on planes, you could separate the pilot’s cabin from the passenger cabin to make a hijack harder. Failing that, maybe there’d be a system for letting ground controllers take over remotely, locking out the pilot, if the craft deviates from its planned route. In any case, one of these small craft probably can’t do enough damage to make it an attractive target for terrorists.

And how about hackers taking control?

That’s a more credible threat. Good cybersecurity is going to be essential.

Won’t flying cars be noisy?

Again—they’re not helicopters , so they don’t have huge blades to disturb the air. Also, the engines will be electric.

Countries are already going crazy trying to regulate drones; how will they regulate flying cars?

These are pretty different problems. Since drones are cheap and anybody can buy one, regulators must stop people from doing malicious or stupid things with them. VTOLs and their pilots, on the other hand, could be certified for safety much like regular aircraft, so existing regulations might not need to be modified much. A bigger question will be whether individual cities decide to allow them in their airspace.

So how long before flying taxis are a common sight in major cities?

Estimates on the panel ranged from “two to five years (but more likely five)” to “10 years.”

Is that plausible? Assuming a big leap in battery capacity, the biggest hurdle is likely to be regulatory. If flying cars are licensed and flown under the same rules as other aircraft, they could start to appear in a few places pretty soon, but managing large numbers of them will require a whole new approach to air traffic management. That, as a somewhat less boosterish panel of expertswarned last year, is going to be a struggle.